Assignment of the Raman active vibration modes of β-Si3N4 using micro-Raman scattering

The vibrational modes of the $\mathrm{\beta -}{\mathrm{Si}}_{\mathrm{3}}{\mathrm{N}}_{\mathrm{4}}$ Raman active bands appearing in the wave number region between 110 and $\text{1100\hspace{0.05em}}{\mathrm{cm}}^{\mathrm{-1}}$ were determined by the polarization and the crystallographic orientation dependence of the Raman intensities of the bands using micro-Raman spectroscopy. The laser beam was focused onto a single grain with the shape of a regular hexagon or elongated hexagon on the sintered ceramic plate. The three intense bands appearing at about 185, 208, and $\text{230\hspace{0.05em}}{\mathrm{cm}}^{\mathrm{-1}}$ were attributed to the vibrational modes of $E_{\text{2g}},$ $A_g,$ and $E_{\text{1g}},$ respectively. The remaining peaks were also assigned to the irreducible representations.